Factors that influence glucocerebroside metabolism will be studied. A newly isolated protein from bovine spleen that acts as a carrier for the glycolipid will be determined by developing monoclonal antibodies and an immunoassay for the protein. The method will allow us to determine its distribution in different organs and subcellular fractions, and to follow changes in concentration during brain development. Another newly isolated protein brom bovine spleen which stimulates the hydrolase, glucocerebrosidase, will be studied in a similar fashion. Since it hs a low moleculr weight, an attempt will be made to determine its sequence of amino acids and to identify the structural features required for biological activity. Antibodies to the two proteins will be injected into mice (if sufficiently cross-reactive) and changes will be sought in tissue levels of glucocerebroside and related sphingolipids, especially the gangliosides, which are synthesized from the lipid. The effect of diet composition will also be investigated.